1. Field of the Invention
The present invention relates generally to weapon sights, and more particularly, to illuminators in weapon sights.
2. Related Art
The soldier has long required an effective, reliable, non-electric low-light illuminator in weapon sights for night-time target acquisition and as a backlight in selected instrument gages, dials and similar devices. For years, the only available light source that satisfied most of these requirements was tritium.
Tritium is a radioactive isotope of the element hydrogen. The radioactive properties of tritium have proved very useful. By mixing tritium with a phosphor that emits light in the presence of radiation in a sealed glass vial, a continuous light source may be formed. Such a light source may be used in situations where a dim light is needed but where using batteries or electricity is not possible. Weapon sights, instrument dials and EXIT signs are several of the most common military/commercial applications of where such a light source is currently used. Tritium weapon sights, for example, help increase night time firing accuracy and the Tritium EXIT signs provide continuous illumination when there is a loss of power.
The use of Tritium, however, carries some serious drawbacks. For example, the use of tritium introduces significant safety risks, hazardous waste concerns and measurable legacy costs. Additionally, if the sealed vials containing the radioactive material is damaged, not only is the light source inactivated, but there may be a low level release of radioactivity that must be addressed. Other drawbacks of tritium include the following: 1) depending upon the amount used, tritium is subject to regulation by the Nuclear Regulatory Commission and improper handling and control of tritium can lead to fines and punitive actions; 2) depending upon the amount used, disposal of tritium-containing materials must be handled as radioactive waste, resulting in significant cost and management oversight of such materials; 3) breakage of tritium vials currently must be treated as a Hazardous Material spill; 4) tritium is a radioactive beta particle emitter and thus, if ingested into the digestive tract, inhaled into the lungs or absorbed into the blood stream through an open wound, tritium poses a known health risk; and 5) the half-life of Tritium is about 14 years, with decay beginning the day the device incorporating the tritium is made. Thus, tritium light sources typically have an effective life of 5-7 years, at which point they become too dim and must be replaced. In sum, radioactive tritium in weapons sights may present a potential health hazard, logistic difficulties and significant life cycle handling and disposal costs.
As such there is a need for improved methods and systems for low-light illumination within weapon sights.